Retarders are one of the most important additives in oilwell cementing for achieving the desired pumping time of cementitious slurry. Retarders are mainly extracted from natural sources, or they are chemically synthesized. However, synthesized retarders can have significant environmental effects. This paper proposes using coffee powder as a biocompatible retarder in oilwell cementing.
This paper discusses a study wherein coffee powder was used as a cement retarder and its effect on other cement slurry properties was evaluated. Cement slurry was prepared and tested as per API RP 10B2 (2005) procedures for thickening time, compressive strength, fluid loss, and rheology. The performance of coffee powder was tested at various concentrations and temperatures up to 350°F. Its retardation activity was compared to a commonly used lignosulfonate-based retarder as well as a synthetic retarder.
Coffee powder exhibited a predictable and linear thickening time behavior with respect to concentration and temperature variation. Testing at different temperatures revealed that coffee powder alone can be used at temperatures up to 350°F without need for a retarder intensifier. A concentration sensitivity study was performed at 125°F, and the coffee powder displayed expected results. To achieve similar performance, lower amounts of coffee powder are necessary compared to the lignosulfonate-based retarder. The performance of coffee powder was similar to the synthetic retarder. Furthermore, coffee powder does not cause adverse effects on other cement slurry properties, such as compressive strength development, fluid loss, and rheology.
This work presents coffee powder performance as a cement retarder. Coffee is readily available, and it demonstrates a high performance and linear concentration response without hampering other cement properties.